Suffering from a hearing loss has an impact on just about every aspect of daily life. Be it conversing with the family and friends or shopping at the local supermarket, the reduced capability of perceiving sound can quickly present challenges unbeknown to persons with normal hearing. Driving a car is no exception. In many ways the in-car setting represents a form of condensed scenario for many of the general issues experienced by persons suffering from a hearing loss. Such issues include:                Misalignment between required and available cognitive resources        Persons with a hearing loss often have problems multitasking if the tasks require auditory attention since they spend a disproportionate amount of mental effort to capture and decipher the sound.        The attention needed to conduct a conversation encroaches on the allocated attention needed to drive a car.        Poor listening conditions        The sound environment has a huge impact on the perception of sound.        In a dynamic environment such as in the car it is not uncommon to experience elevated noise (traffic, children, radio) or poor acoustic conditions in general (hard surfaces, external noise, multiple sound sources, etc.).        Poor conversation practice        Focus, visual contact (e.g. lip reading) and the use of gesticulation are critical elements of conducting a conversation when having a hearing loss.        In the car many of these can be difficult to achieve due to the seating positions (front vs. rear seats) and the need of the driver to keep his or her eyes on the road.        
Hearing-impaired persons thus often experience problems when listening to radio, navigation devices and mobile phones as well as when communicating with other passengers in the car. These problems are in many ways similar to other every-day problems encountered when living with a hearing loss, but can potentially be more hazardous due to the safety-critical situation of operating a car. In the past, various measures have been proposed to remedy such problems.
Furthermore, a common need for many hearing-aid users is to be able to get a clear audio signal directed into the hearing aid from another electronic device, such as a mobile phone or a portable music player. To satisfy this need, hearing systems often comprise an audio gateway device, such as e.g. the Oticon Streamer (registered trade mark). An audio gateway device is a device that takes audio inputs from other devices with audio output, transcode the audio inputs and transmits one or more of them to the hearing aid. The audio input may come from different sources, e.g. a Bluetooth (registered trademark) data connection, an analog audio-input or a wireless microphone. Some Bluetooth-equipped audio gateway devices also act as a two-way communication device with mobile phones, enabling the hearing aid to work as a hands-free headset in conjunction with a microphone comprised in or connected to the audio gateway device. Audio gateway devices also often provide remote control functionality for the hearing aids.
The communication between the audio gateway device and the hearing aids may take place via a portable teleloop converter or a portable frequency modulation (FM) or amplitude modulation (AM) radio system. Alternatively, Near-Field Magnetic Induction (NFMI) may be used for streaming audio to the hearing aid in an almost lossless digital format. The NFMI technology makes it possible to transmit the high quality signal using very little power, but only within a limited range. For this reason, audio gateway devices using NFMI often comprise a neck-loop antenna to improve the signal strength and range. Without a neck-loop antenna, the range is typically about 30 cm or less. With a neck-loop antenna, the range may be increased to about 50 to 60 cm. In both cases, the relative orientation of the antenna and the receiving coil has a strong influence on the achievable range. Due to the characteristics of the antenna it is necessary to wear the loop around the neck to avoid dropouts in the signal.
Patent application WO 2008/015293 discloses a hearing system comprising one or two hearing devices, which are capable of receiving wireless audio signals from in-car devices, such as a car stereo, a CD player and/or a navigation system. The hearing system comprises a processing unit receiving the audio signals from the in-car devices and streaming one or more of the audio signals to the hearing devices. The signals may be transmitted via radio, e.g. according to the Bluetooth standard. The hearing system may comprise additional devices, such as a wireless remote control or a remote microphone, meant to be worn or carried by the hearing-device user. The output level of the hearing devices may be controlled from the remote control and/or from a user control, which may be e.g. mounted in the steering wheel. A control unit ensures that the output level and/or the amplification of microphone signals in the hearing devices is kept above a minimum value when the hearing devices receive data from the processing unit.
Patent application US 2006/0039577 discloses a hearing system comprising a hearing assistance device and a wireless communications adapter. The wireless communications adapter receives audio signals from remote devices via radio, e.g. according to the Bluetooth standard, and transmits the audio signals to the hearing assistance device via NFMI signals. A remote device may e.g. be a cellular phone. The wireless communications adapter may be embodied as a pendant to be worn in a neck loop, which simultaneously functions as an inductive antenna for the NFMI signals. The wireless communications adapter may comprise a microphone, a volume control and various buttons, the settings of which may be transmitted to the hearing assistance device. The wireless communications adapter may be battery-powered.
Teleloop, FM, AM and NFMI transmitters used in or with body-worn audio gateway devices, such as the wireless communications adapter mentioned above, are typically designed to have a limited communication range in order to save battery energy. Due to the smaller battery sizes typically used in hearing devices, saving energy is even more important in systems with bidirectional communication between the hearing devices and the audio gateway device. Limiting the communication range is possible because the communication between the audio gateway device and the hearing devices typically takes place over a short distance, e.g. between the neck and the ears of the hearing-device user or between a breast pocket and the ears. In the following, limited-range electromagnetic signals used for communication between the audio gateway device and the hearing devices over such short distances are generally referred to as “close-range electromagnetic signals”. In communication between hearing devices and other devices, the use of close-range electromagnetic signals is generally preferred over technologies with larger ranges, such as e.g. Bluetooth radio, since the use of close-range electromagnetic signals enables much lower power consumption in the hearing devices.
A body-worn audio gateway device is typically used outside the car, where it may provide for e.g. hands-free mobile telephony and listening to music streamed directly to the hearing devices. It may also be used when driving, but with a number of disadvantages. Due to the restricted body position when driving, the user typically makes more extreme head movements than outside the car. Since the transmission range is limited, such head movements may lead to poor reception of the close-range electromagnetic signals and thus to distortion or pauses in the streamed audio signals. For audio gateway devices with a neck loop, the neck loop must be worn at all times, which may be tiring. The neck loop or the pendant may become entangled with the seat belt, and user controls on the audio gateway device can be difficult to reach and see. This increases the risk of accidentally activating functions and/or changes in the hearing systems, such as e.g. lowering or raising the gain, muting, switching inputs etc. Reacting to such accidental events may distract the driver. Furthermore, the battery powering of the audio gateway device often limits its duration of use.
When a user wearing a hearing system with a body-worn audio gateway device enters a car equipped with an in-car system, such as the one described further above, he or she may thus want to switch to the in-car system for streaming audio signals to the hearing devices. This typically requires manual interaction e.g. to trigger the switch-over and to maintain hands-free operation of a carried mobile phone. Similar considerations apply when leaving the car. Furthermore, if the audio gateway device is not shut off in the car, the audio gateway device and the in-car system may disturb each other, which may lead to malfunction of the systems, more troublesome interaction with the devices and systems and/or reduced audio quality.
There is therefore a need for a hearing system and a method for operating a hearing system, which reduce the above mentioned problems associated with switching over from the outside-car environment to the in-car environment and/or vice versa.
It is an object of the present invention to provide a method for operating a hearing system, which method reduces the above mentioned problems. It is a further object of the present invention to provide a hearing system, which reduces the above mentioned problems. A further object is to provide audio gateway devices that may be used in such methods and systems.